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基于基模高斯光束衍射倍率因子M2近似为1这一条件,利用几何光学成像原理来模拟基模高斯光束通过透镜的成像规律,给出了一种计算透镜像方光轴上不同点处高斯光束光斑半径的简便方法。该方法通过选取合适的物距lc,高斯光束的衍射倍率因子M2近似为1,激光束经透镜聚焦与普通平行光束的聚焦过程相似,符合几何光学成像原理。通过几何光学方法和ABCD定理推导出了高斯光束光斑半径表达式,并进行数值计算,利用MATLAB软件对数值进行拟合。拟合结果表明;此方法计算出的光斑半径符合较好,满足瞬态高温测量中探测器光敏面对激光光斑尺寸的要求。
Based on the condition that the diffraction factor M2 of the fundamental mode Gaussian beam is approximately 1, the principle of geometrical optics imaging is used to simulate the imaging rule of the fundamental mode Gaussian beam passing through the lens. A method of calculating the Gaussian beam at different points along the optical axis A simple method of spot radius. By choosing a suitable object distance lc, the diffraction factor M2 of the Gaussian beam is approximately 1. The focusing of the laser beam by the lens is similar to that of the ordinary parallel beam, which accords with the principle of geometrical optics imaging. The geometrical optics method and ABCD theorem were used to deduce the expression of Gaussian beam spot radius, and the numerical calculation was carried out. The software was used to fit the numerical value. The fitting results show that the radius of the spot calculated by this method is in good agreement with the requirement of the laser spot size of the detector photosensitive surface in transient high temperature measurement.